diff --git a/src/test/policyestimator_tests.cpp b/src/test/policyestimator_tests.cpp
--- a/src/test/policyestimator_tests.cpp
+++ b/src/test/policyestimator_tests.cpp
@@ -69,7 +69,7 @@
             }
         }
         // Create blocks where higher fee txs are included more often
-        for (int h = 0; h <= blocknum % txIds.size(); h++) {
+        for (size_t h = 0; h <= blocknum % txIds.size(); h++) {
             // 10/10 blocks add highest fee transactions
             // 9/10 blocks add 2nd highest and so on until ...
             // 1/10 blocks add lowest fee transactions